Conversion of hydrocarbon feed to useful products such as fuel, olefins, etc., is now well known. Many processes have been developed to crack crude hydrocarbon to produce useful products. Among the conventional processes are pyrolysis cracking and catalytic cracking processes. In recent years, both pyrolysis cracking and catalytic cracking have implemented systems in which particulate solids are used as the heat source to promote cracking of the hydrocarbon feed.
In effect, particulate solids, either inert or catalytic, are heated and introduced into a cracking zone with hydrocarbon feed. The hydrocarbon feed is cracked in the cracking zone and the heated particulate solids lose heat and are fouled or contaminated with the tars and other heavy components of the hydrocarbon feed. Thereafter, typically the contaminated solids are regenerated for re-use in cracking hydrocarbon feed. Regeneration entails burning the contaminants from the solids and elevating the temperature of the particulate solids to the level necessary to crack the hydrocarbon feed.
Each cracking process in which particulate solids are used requires delivery and separation means to both engage the solids with the hydrocarbon feed and to separate the solids from the cracked product gases produced in the process.
Recently, a process and an apparatus have been developed by Stone and Webster Engineering Corporation that efficiently and effectively separates particulate solids from the cracked gases leaving a cracking reactor. U.S. Pat. No. 4,433,984 and others describe the separation process and-apparatus that has minimized the contact time in separation of the particulate solids and cracked gases while achieving separation to a level desired for terminating cracking reactions.
Similarly, Stone and Webster Engineering Corporation has developed a process and an apparatus for delivering particulate solids to a service such as a fluidized bed furnace which eliminates moving mechanical parts and thereby enhances the function and reliability of the delivery system. The process and apparatus are described in U.S. Pat. No. 4,459,071. Essentially, the system relies on regulated pressure differentials to promote or interrupt the flow of solids to a location.
In addition, Stone and Webster Engineering Corporation has developed a process and apparatus for injecting hydrocarbon feed into a moving path of hot particulate solids to achieve rapid and complete cracking of the hydrocarbon feed. U.S. Pat. No. 4,338,187 and others describe a hydrocarbon feed and hot particulate solids feed system that achieves rapid mixing of the feed and solids and the desired attendant rapid cracking.